Mr Williams said that authorities had put out alerts “in the state of Ohio and beyond” over the “senseless” incident, and urged people not to approach the suspect, who he said was likely to remain armed and dangerous.

The Cleveland police department issued a photo of Mr Stephens on its website, describing him as a 6ft 1in (1.9m) tall black male of medium complexion.

Image copyrightCleveland Police

Image caption
Police issued a photo of the suspect

He is thought to be driving a white or cream-coloured SUV (sports utility vehicle).

Mr Williams said that the victim appeared to have been selected at random in what he described as a “senseless” murder.

He added that Mr Stephens “clearly has a problem” and urged him to come forward in order to “receive the help that he needs”.

The Federal Bureau of Investigation (FBI) is collaborating with local police as it investigates the incident, CNN reports.

The mayor of Cleveland, Frank Jackson, said that he wanted Mr Stephens to know that “he will eventually be caught”.

It is not the first time that a fatal shooting has been captured on Facebook Live. Last June, a man was shot dead while live-streaming a video of himself on the streets of Chicago. In March, an unidentified man was shot 16 times while broadcasting live.

Facebook’s live-streaming feature allows anyone to broadcast online in real time. It was launched in 2010 but has become more central to the social network’s strategy in recent months.